The unique steel lattice design of the Olympic stadium in Beijing looks set to make it one of the symbols of our age - and to engender awe at the creative imagination of China. It will be the stage for the opening ceremony, the athletics events and the medal awards.

But Ai Weiwei, the Chinese artist who conceived the "bird's nest" design with Swiss architects -Herzog & de Meuron, says he wants nothing to do with the stadium's propaganda use. "The joy of design is already there, the rest is rubbish. I have no interest in associating myself with the Olympics or the state. I hate the kind of feeling stirred up by promotion or propaganda. I instinctively avoid it. It's the kind of sentiment when you don't stick to the facts, but try to make up something, to mislead people away from a true discussion. It is not good for anyone."

Ai has good reason to oppose propaganda. In an anti-rightist purge, his father, Ai Qin, one of China's greatest modern poets, was banned from publishing for the better part of two decades in the late 1950s. Exiled to Xinjiang, he was forced to clean latrines. Why, then, did his son take part in a project with such obvious party uses?

"I was not hired by the state, but by a design team in Switzerland. No one in the state here would ever hire me for a project like this. Even if they tried, I would not do it. I have too many reasons not to do it," he says, but adds that he has no regrets. "Design in itself has a meaning for me. Whether a stadium or a toilet seat, the form is interesting, as are the human activities that relate to it ...The stadium is a very bold design for a nation that wants to prove itself part of the international family, to show we share the same values. It represents a lot of passion and energy. As an architectural work, it stands for this moment in history. I think families will take their children and their imaginations will be stimulated about what human effort is capable of."

What makes it unique, he believes, is that there is no need for interior design. "Everything is one. The structure is its own art form. From inside and outside it is one thing. It is a totality. That makes it very special conceptually. That is much more important than the look." Ai feels the "bird's nest" tag detracts from it. "If you look at it long enough, it becomes something else. That is why I never look at it. I tell them I will never go. They say, 'this guy is crazy'." He will not be there for the opening -ceremony on August 8 2008. "If my mind is still clear at that time, I would rather be disconnected or forgotten."

There are harsh words too for his contemporary, the director Zhang Yimou, who is choreographing the opening ceremony in consultation with Steven Spielberg. "All the shitty directors in the world are involved. It's disgusting," says Ai. "I don't like anyone who shamelessly abuses their profession, who makes no moral judgment. It is mindless. I very openly criticise the tendency to use culture for the purpose of propaganda, to dismiss the true function of art and the intellect. Everybody has this tendency not to talk about the past. The only thing left is to try to entertain and celebrate. It's crazy."

In his career, Zhang has been criticised by the authorities and their opponents alike, while Spielberg has said he prizes the 2008 games for promoting "universal moral principles". And in any case, isn't Ai Weiwei equally involved? "I have clear political standards. It is not opposition to the state, but rather in fighting for individualism and freedom of expression, freedom of human rights and justice. They sound like big words, but they are not when you grow up in such a society. It is a pity we have to think about those things, but still, it is a fact.

"If you read newspapers today you see the problems created by this structure and by the effort to maintain power. It is against everything that human society should be fighting for. I am just a normal person, but happily I have become a notable person. That means something to me only because it gives me a better chance to fight.

"You cannot walk 100m in Beijing without questioning why you live in this city. Yet they celebrate the Olympics. It is very ironic. Look at the air in the past week. But it is no more disgusting than the political conditions here."

I ask Ai why he is speaking so strongly, and if he fears repercussions? "It is the only thing I am not worried about. I am 50 years old. My father was in jail when he was 30, then he was sent into exile," he says. "It is never too late. A person has to do something. We must continuously act by ourselves, to make decisions to participate or to resist. We must draw our own lines."